1. Field of the Invention
The present invention relates to a semiconductor device. In particular, the present invention relates to a semiconductor device capable of storing data even when power supply is stopped and a method for driving the semiconductor device.
2. Description of the Related Art
As for semiconductor devices such as micro processing units (MPU), improvement of operating frequency and downsizing of elements have been researched and developed to improve performance and reduce power consumption. On the other hand, the power consumption of semiconductor devices due to leakage power or the like caused by downsizing of elements is increased.
In recent years, to solve the problem of increased power consumption, a technique for drastically reducing power consumption has attracted attention in which a volatile register and a nonvolatile register are combined in a semiconductor device, data is backed up and recovered between the volatile register and the nonvolatile register, and supply of power to the semiconductor device is stopped and restarted actively (see Patent Document 1).